With the rising of smart vehicles, V2X are introduced in 3rd Generation Partnership Project (3GPP) to support future vehicle related services. The V2X services may be categorized as Vehicle-to-Vehicle (V2V), Vehicle-to-Network (V2N) and Vehicle-to-Person (V2P) according to application scenarios of the V2X services.
At present, an enhanced mode based on direct communication between terminals (D2D) is adopted to support the Vehicle-to-Vehicle (V2V). For Vehicle-to-Network (V2N), there is no obvious difference from the communication mode between a cell phone and a cellular network. For Vehicle-to-Person (V2P), most of the communication technologies may adopt the communication mode of the Vehicle-to-Vehicle (V2V). Since vehicles in the Vehicle-to-Vehicle (V2V) communication are not sensitive to power consumption, the power consumption optimization is not considered. However in the Vehicle-to-Person (V2P) communication, due to the participation of hand-held terminals (i.e. normal cell phone), the power saving issue should be solved.